Project Summary/Abstract Long-duration low-level (LDLL) noise exposures can enhance or depress sound-evoked activity in the auditory cortex (AC), but it?s unclear if these neuroplastic changes originate in the AC or are inherited from lower levels of the auditory pathway. To address this, recordings will be obtained from the cochlea, inferior colliculus (IC) and AC to determine the magnitude and direction of change. To determine if LDLL noise exposures disrupt the neural input to the central auditory pathway, we will evaluate the inner hair cell pre- synaptic ribbons and key proteins expressed on the post-synaptic type I afferent fibers. Our working hypothesis is LDLL noise exposure depresses the neural output of the cochlea, but the central auditory pathway compensates for this by enhancing neural gain at progressively higher levels of the auditory pathway.